Selectively enabled quality of service policy

ABSTRACT

A computer system that implements a quality of service policy. Information defining the quality of service policy is stored in a central location, such as a server within an enterprise. Policy management software on clients in the network download quality of service policy information from the central location to the clients. Within a client, a portion of the policy information is selected based on its applicability to a particular connection. The selected information is cached with an association to the connection so that, as datagrams are generated for transmission over the network, relevant policy information is quickly accessed for use in controlling transmission characteristics of datagrams sent using that connection. The policy information is applied on a datagram-by-datagram basis, allowing policy information to be selectively applied based on network type. Policy information may be selectively applied to those datagrams transmitted over a managed network. This approach allows a client configured to apply a quality of service policy within an enterprise network to operate without applying the policy when removed from the enterprise network.

BACKGROUND

In computer systems, particularly enterprise networks, managing “qualityof service” can be important. In this context, “quality of service”relates to how well users' expectations of the performance of the systemare met. In a networked computer system, a user's perception, andtherefore quality of service, is heavily influenced by the latency withwhich different types of information are transmitted over the network.For example, a network may deliver datagrams with latencies that varybetween microseconds and several hundreds of milliseconds, depending onnetwork loading. Such latencies will be adequate for many applications.However, for some applications, such as VoIP and other applications thatprovide an interactive experience to a user, such variations in latencywill be noticeable, causing the user to perceive a low quality ofservice.

Poor quality of service frequently occurs when too many datagrams needto be transmitted through a network “bottleneck.” Datagrams are queuedat the bottleneck, creating latency. In an enterprise, a bottleneck mayoccur at a connection to the Internet or other similar gateway at theedges of the enterprise network. Bottlenecks can also occur within anenterprise network, such as at a trunk line connecting zones within thenetwork.

To improve quality of service, network components can be designed toprocess datagrams with different priorities. Datagrams for which highlatency creates a poor user experience may be assigned a higherpriority. Giving priority to these datagrams keeps latency for thosedatagrams low, even at a bottleneck, and increases the overall qualityof service. Alternatively, datagrams for which high latency hasrelatively little effect on user perception of the quality of thenetwork may be transmitted with lower priority.

The ability to manage quality of service has been available in somecomputer systems. For example, codes, called ToS or DSCP codes, may beinserted in datagram headers. A router or other network elementconstructed to recognize ToS or DSCP codes will typically maintaindifferent queues and assign a datagram to a queue based on the DSCP orToS code. Datagrams in a queue associated with a higher priority codewill be given higher priority in selecting the next datagram to process,which reduces latency for higher priority datagrams relative to lowerpriority datagrams.

Additionally, drivers that manage the transmission of datagrams over anetwork can be equipped to “throttle” datagram transmission inproportion to a setting provided with a datagram. When a throttlesetting is applied to a datagram, the driver may buffer the datagrambefore transmitting it over the network to keep the rate of transmissionbelow a rate specified by the throttle setting.

SUMMARY OF INVENTION

In one aspect, the invention relates to a computer system in which aquality of service policy may be implemented. The computer system hasfeatures that are useful in many environments, including computersystems that are part of enterprise networks.

In one aspect, the invention relates to a computer system that sensesnetwork characteristics and selectively applies a quality of servicepolicy based on the sensed network characteristics. This capabilityallows a portable client, such as a laptop, to apply a quality ofservice policy while connected to an enterprise network or other managednetwork but to transmit without applying the quality of service policywhen connected to networks outside of the enterprise network.

In another aspect, the invention relates to software for a clientcomputer. The software includes a network interface containing a datafield to indicate a network type. This field can be used in selectivelyapplying quality of service parameters based on network type. Thisarchitecture allows quality of service parameters to be applied based onnetwork type on a datagram-by-datagram basis with low overhead.

In another aspect, the invention relates to a method of operating acomputer system with a portable client that may be connected to thenetwork in multiple locations. In one location, which may be an office,when the client is connected to a network, a quality of service policyis applied. When connected in a second location, which may be a user'shome, the client may be connected to the network and apply the qualityof service policy but be connected to a second network without using thequality of service policy. This capability facilitates use of a qualityof service policy in a managed network with portable clients, withoutinconveniencing the users of the portable clients.

The foregoing is a non-limiting summary of the invention, which isdefined by the attached claims.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 is a sketch of a computer system, including an enterprise networkusing a quality of service policy according to an embodiment of theinvention;

FIG. 2 is a software block diagram of a prior art client computer;

FIG. 3 is a software block diagram of a client computer adapted toimplement a quality of service policy according to an embodiment of theinvention;

FIGS. 4A, 4B, and 4C are sketches illustrating data structures that maybe used in a system implementing a quality of service policy accordingto an embodiment of the invention; and

FIG. 5 is a flow chart showing a method of operation of a computersystem to implement a quality of service policy according to anembodiment of the invention.

DETAILED DESCRIPTION

A quality of service policy is most useful within a company or otherenterprise. Though applying a quality of service policy is intended toincrease user perception of network performance, it does not actuallyincrease the amount of information that the network can transmit.Rather, applying a quality of service policy changes the allocation ofnetwork bandwidth so that higher priority transmissions are less likelyto experience network delays.

But, decreasing latency for some transmissions comes at the expense ofincreased latency for those clients that use a policy that specifieslower priorities for their message traffic. A company or enterprisebenefits from using a quality of service policy on its networks becauseits own higher priority traffic benefits from more available bandwidth.In other network environments, applying a quality of service policy mayactually be counterproductive. Applying the policy causes a user torelinquish network bandwidth, with no offsetting benefit.

We have recognized that implementing a quality of service policy in anetwork having portable clients can lead to undesirable operatingcharacteristics if the portable clients are connected to other networks.For example, many corporate computer users have laptop computers.Frequently, those users connect their laptops to an enterprise networkmanaged by the company while at a company office. It is desirable foreach laptop computer to contain software implementing a quality ofservice policy while connected to a corporate network. However, laptopcomputers are often disconnected from the enterprise network and used athome or in other settings where the laptops may be connected to othernetworks. Using the quality of service software while the laptopcomputer is connected to another network may cause the laptop computerto give up network bandwidth to other clients on the network, creatingdelays in messages sent from the laptop.

To avoid unnecessary delays in message transmission caused byapplication of a quality of service policy configured for an enterprisenetwork when a client from that enterprise network is used in otherenvironments, we have developed a system to implement a quality ofservice policy that allows transmission characteristics of datagrams tobe set on a datagram-by-datagram basis. One factor in applyingtransmission characteristics in accordance with a quality of servicepolicy is whether the client, at the time it transmits a datagram, isconnected to a managed network. The system may use networkcharacteristics that can be sensed by the client to determine whetherthe client is transmitting over a managed network, allowing the systemto be simply used without express user action.

As used herein, a quality of service policy is information that definesconditions under which one or more datagram transmission characteristicsare set or altered. The transmission characteristics described hereininfluence perceived network latency, but any suitable characteristicsmay be specified as a portion of a quality of service policy. Also, thequality of service policy may be specified in any suitable form and mayexist in multiple forms. For example, the policy may be defined inhuman-readable form and may also be embodied as a computer-readable datastructure.

FIG. 1 illustrates an embodiment of a computer system that employs aquality of service policy. In the example of FIG. 1, the computer systemincludes enterprise network 100, which is configured to employ a qualityof service policy. Enterprise network 100 includes clients 110A and110B. A client may be any device connected to the network that injectsdatagrams into the network for transmission to other networked devicesreachable through the network.

In this context, the term “datagram” refers generally to a unit ofinformation formatted for transmission over a network. Sometimes,datagrams are called “packets” or “messages” or may be given other namesin connection with networks using specific protocols. Use of the generalterm “datagram” is intended to signify that the inventive conceptsdescribed herein are broadly applicable to communications regardless ofspecific format or network protocol.

In this example, client 110A is a desktop workstation and client 110B isa portable device, such as a laptop computer. However, any suitablecomputing device, whether now known or hereafter developed, may serve asa client. In this example, two clients 110A and 110B are shown forsimplicity. An actual enterprise network may have many clients.

A network traditionally includes one or more switching devices thatinterconnect devices in the network. A switching device directsdatagrams transmitted over the network to the appropriate device basedon header information in the datagram. There are many types of switchingdevices, such as devices commonly called “switches,” “hubs” and“routers.” The specific network architecture and hardware is not alimitation of the invention. Accordingly, router 116 is used as anexample of a switching device.

FIG. 1 shows a simplified enterprise network 100. As used herein, theterm “enterprise” does not connote a network or company of any specificsize, but refers generally to a group of computing devices for which aperson or entity may provide control or other operational information.In the embodiment described, policy information defining operation ofmultiple clients is provided by a network administrator and stored ondatabase 114.

In FIG. 1, enterprise network 100 is connected through gateway 118 to abroader network. In this example, the broader network may be theInternet 130 and the connection may be made through a trunk line 120.However, it is not necessary for enterprise network 100 be connected toa public network. For example, gateway 118 may connect enterprisenetwork to other network zones managed by the same enterprise thatmanages enterprise network 100. The connection through gateway 118allows client computers 110A and 110B within enterprise network 100 tocommunicate with other devices outside of enterprise network 100. Forexample, client computers 110A and 110B may communicate with a server150 through router 140 that is connected to Internet 130.

FIG. 1 shows a network client 110C that may be a portable device, suchas a laptop computer. A portable device may be connected to enterprisenetwork 100 through a network drop or other access point within anoffice 101 operated by the enterprise that manages enterprise network100. Because of the portable nature of client 110C, client 110C may alsobe connected to either enterprise network 100 or other networks, such asInternet 130, from locations remote from office 101. In the example ofFIG. 1, client 110C is connected to Internet 130 while physicallylocated in a user's home 161. Client 110C may connect to Internet 130through an Internet service provider using an Internet connection 165.To make a connection to enterprise network 100, client 110C may usevirtual private network (VPN) software to create a VPN connection 163.But, any suitable manner may be used to make a network connection.

FIG. 1 provides examples of where “bottlenecks” may occur for enterprisenetwork 100. Switching devices, such as routers 116 and 140 and gateway118 may create bottlenecks. Likewise, trunk line 120 could createbottlenecks. Accordingly, it may be desirable to use a quality ofservice policy within enterprise network 100 to reduce the impact ofthese bottlenecks on user perception of performance. It may also bedesirable to apply the same quality of service policy to transmissionsby client 110C while using VPN connection 163. However, when client 110Cuses Internet connection 165, it is not necessary to apply a quality ofservice policy from enterprise network 100. To the contrary, applying aquality of service policy from enterprise network 100 to transmissionsby client 110C through Internet connection 165 may actually detract fromthe experience for a user of client 110C. As described in greater detailbelow, client 110C may be programmed with software that selectivelyapplies a quality of service policy based on the type of network towhich a client is connected.

To facilitate the implementation of policies within enterprise network100, enterprise network 100 also includes server 112. In this example,server 112 acts as a source of policy information stored in database114. Clients such as 110A, 110B and 110C (when connected to enterprisenetwork 100) connect to server 112 to download policy information fromdatabase 114. The policy information stored in database 114 mayrepresent any type of policy information, such as configuration settingsfor communication software, formatting options to apply to documents orother policies.

Policy servers, such as server 112, are known in the art. For example,Microsoft, Inc. provides an enterprise application called “ActiveDirectory” that includes a server configured to provide policyinformation to multiple clients in an enterprise network.

Enterprise network 100 may be conveniently implemented with anapplication, such as Active Directory, that would otherwise exist in anenterprise network. However, enterprise network 100 differs fromconventional enterprise networks in that the policy information indatabase 114 relates to a quality of service policy instead of or inaddition to other policy information as known in the art. In addition,devices that receive the policy information are adapted to apply thequality of service policy information.

In embodiments described herein, policy information is in the form of aset of rules. However, any suitable format for representing policyinformation may be used. Each rule may specify one or more conditionsand one or more transmission characteristic to be used when theconditions are met. In the embodiments described herein, thetransmission characteristics specified as part of a quality of servicepolicy rule may be used to influence the relative latency of a datagramtransmitted with those characteristics. The transmission characteristicsmay be codes, such as DSCP or ToS codes, that are inserted in messageheaders. Routers or other network devices may use these codes toprioritize datagrams for transmission or forwarding.

Transmission characteristics included in a policy may additionally oralternatively specify a maximum rate at which data is to be injectedonto the network. A client or other device that transmits datagramsusing such a characteristic may ensure the maximum rate is not exceededby “throttling” transmission of datagrams. A device may “throttle”transmissions by buffering datagrams to be transmitted to leavesufficient time between datagrams such that the maximum rate is notexceeded. However, any desired approach to throttling may be used.

Regardless of the specific form in which the policy information isstored in database 114, once downloaded to a client computer, the clientcomputer can implement the policy as applicable to datagrams transmittedby that client. As a client initiates transmission of a datagram, itdetermines which portion of the policy is applicable to that datagramand appropriately applies it. In some embodiments, a client computer maysense the type of network to which it is connected and only apply thepolicy while the client is connected to a managed network.

In some embodiments, a quality of service policy is implemented bysoftware within the operating system of the client computer.Implementing a quality of service policy from within the operatingsystem software provides advantages over the conventional approach ofrequiring each application that generates datagrams to specifyapplicable transmission characteristics. One advantage is that nochanges are required to applications in order for the application toimplement a quality of service policy. Therefore, a networkadministrator can quickly and easily set or modify a quality of servicepolicy as a network or network usage changes. In addition, the qualityof service policy can be adapted based on operating conditions of theclient, allowing an easy way to selectively apply a quality of servicepolicy when a client is connected to a managed network.

Even though the quality of service policy is implemented differentlythan in the prior art, conventional components for implementing aquality of service policy may nonetheless be employed. FIG. 2 providesan example of a software architecture such as may be found in clientcomputers as known in the art. FIG. 2 shows components of an operatingsystem as is conventionally found on a client computer.

In FIG. 2, network stack 214 has an interface 212 through whichapplication 210 may pass a message or other information for transmissionover a network. Application 210 may represent a word processor, a webbrowser or other application program executing on a client computer.Traditionally, a client computer includes multiple applications, butonly one is shown for simplicity. Stack 214 may be a network stack as isfound in an operating system, such as the WINDOWS® operating system.

Network stack 214 formats information passed through interface 212 asappropriate for transmission as one or more datagrams. Network stack 214passes information for transmission to a network interface. FIG. 2 showsnetwork interfaces 215A . . . 215C. A client computer may contain anynumber of network interfaces. A network interface is a logical entitycreated by network stack 214 to represent a physical or virtual networkadapter. For example, client 110C may contain a network interfaceproviding VPN connection 163 and a separate network interface providingnetwork Internet connection 165. More generally, each network interfacemay provide an interface to a physical device or a “virtual” device,such as the VPN.

Network interfaces 215A, 215B and 215C pass information specifyingdatagrams to driver 216. Driver 216 controls network interface card(NIC) 218 to transmit the datagrams over the network.

In the embodiment of FIG. 2, interface 212 may be adapted to receive, inaddition to information specifying a message to be transmitted,information specifying transmission characteristics. In this example,the transmission characteristics specified are a throttle rate and aDSCP value. This information is passed through network stack 214 todriver 216. Driver 216 inserts the DSCP value into the header portion ofeach datagram it sends to transmit any portion of the message initiatedby application 210.

Driver 216 also receives the throttle value provided by application 210in conjunction with a datagram to be transmitted. Driver 216 uses thethrottle value to limit the rate at which datagrams are sent. Ifapplications within a client computer are coded to generate quality ofservice parameters in association with messages initiated by theapplications, the datagrams encapsulating those messages will betransmitted with characteristics that implement the policy.

FIG. 2 also shows that the network layer of operating system softwarewithin a client includes a network location awareness component (NLA)221. NLA 221 may determine properties about networks to which a clientcomputer is connected. One of the properties that NLA 221 may determineis the type of network to which the client is connected. NLA 221 may,for example, determine whether the client is connected to a managednetwork. Conventional approaches may be used to determine whether theclient is connected to a managed network. For example, NLA 221 mayidentify that the client is connected to a managed network by finding adomain server on the network to which the client is connected. One wayin which a domain server may be identified is by obtaining a deviceaddress for the client and attempting to extract from that address anaddress of a domain controller. A device address for each networkconnection may be obtained from each network interface 215A . . . 215C.NLA 221 may then attempt to communicate with the domain controller atthe extracted address. If NLA 221 detects a domain controller, it canconclude that it is communicating over a managed network. However, anysuitable method for determining whether a client is connected to amanaged network may be used.

As shown in FIG. 2, a client computer may include the client portion ofa policy service used within an enterprise network. Client policyservice 250 may be a software module that controls the client to receivepolicy information from a policy server, such as policy server 112 (FIG.1). However, in the prior art embodiment in FIG. 2, policy service 250did not receive quality of service policy information because suchinformation needed to be encoded as part of an application 210.

FIG. 3 shows a software architecture according to an embodiment of theinvention. In the embodiment of FIG. 3, application 310 need not bespecially configured to implement a quality of service policy.Application 310 simply passes information for transmission throughinterface 312 to network stack 314. Operating system components apply aquality of service policy to the message, if application of the policyis appropriate. An advantage of this architecture is that messages fromany application may be subject to a quality of service policy even ifthe application is not customized to provide quality of serviceinformation in conjunction with messages it generates.

FIG. 3 shows a software architecture for client software that includes aquality of service (QoS) policy component 320. QoS policy component 320provides transmission characteristics for datagrams as they are beingprocessed by stack 314. In the illustrated embodiment, stack 314 callsan interface to QoS policy component 320 each time stack 314 processes amessage to be transmitted. QoS policy component 320 returns valuesdefining transmission characteristics. The transmission characteristicsmay be the same as those controlled in conventional systems. In thisexample, the transmission characteristics are a throttle rate and a DSCPvalue, but any suitable transmission characteristics may be specified toimplement a quality of service policy.

QoS policy component 320 may receive policy information from acentralized location, such as policy server 112 (FIG. 1). Client policyservice component 250 is constructed to generally perform functionsneeded to obtain policy information but is customized to obtain specifictypes of policy information through the use of client side extensions.Here, QoS client side extension 322 is configured to provide clientpolicy service component 250 with information needed to identify qualityof service policy information on server 112. In addition, QoS clientside extension 322 provides control information necessary for clientside policy service component 250 to store policy information in theappropriate locations.

In the embodiment illustrated, QoS client side extension 322 identifiesto client policy service component 250 that QoS policy registry 324 isthe destination for downloaded quality of service policy of information.In addition, QoS client side extension 322 provides control informationto QoS inspection module 328. Such control information may providenotification from QoS client side extension 322 to QoS inspection module(328) that a policy update has occurred or otherwise coordinate actionof the components.

In the embodiment illustrated, client policy service component 250obtains policy information from server 112. To ensure each clientcontains up to date policy information, client policy service component250 may periodically pull information form the server. However, anysuitable timing and method of obtaining information from server 112 maybe used.

As one example of another method of obtaining policy information, it isnot necessary that all clients within an enterprise network obtainquality of service policy information from the same server or from asingle server. Each network domain may have a domain server, which mayalso serve as a policy server. Further, even if domain servers areprovided as a centralized repository of policy information, anenterprise network may additionally include other policy servers thatprovide policies for the entire network.

As another example of a further source of policy information, FIG. 3shows that each client may have a client policy registry 326. Clientpolicy registry 326 may be a data structure containing policyinformation specific to the client containing client policy registry326. Though the invention facilitates centralization of policyinformation, policy information also or additionally may be placed inclient policy registry 326 on a client computer in any desired way. Forexample, it may be placed by a user operating the client computer, by anapplication when it is installed on that client computer or by a networkadministrator.

FIG. 3 shows that client policy information is stored in a separate datastructure from policy information downloaded from server 112. It is notnecessary that the information be stored in a separate location or in aseparate data structure. In the described embodiment, policy informationfrom different sources is stored in a way that allows specific policiesto be associated with a source so that, if a client receivesinconsistent policies from different sources, it can reconcile theinconsistencies based in part on the source of the policies.

If a client obtains policy information from multiple sources, the clientmay reconcile the policy information to determine which policy to applyin the event of a conflict. In the described embodiment, policyinformation from multiple sources is reconciled according to the networkhierarchy. For example, client policies, as the lowest level of thehierarchy, are applied only if not inconsistent with policies at anyother level. At the other extreme, network policies are at the highestlevel of the hierarchy and may be applied in all instances.

In the embodiment illustrated, policies are specified as rulescontaining conditions. If the conditions of two rules are determined toboth apply to the same transmission, then the highest priority rule isapplied to that transmission. However, any suitable method ofreconciling different policies may be employed.

To avoid the computational overhead of applying a QoS policy on amessage-by-message or datagram-by-datagram basis, QoS policy component320 may store policy information in a manner that allows fastidentification of appropriate transmission characteristics for eachtransmission.

In some embodiments, fast identification of appropriate transmissioncharacteristics is achieved by storing policy information associatedwith each connection formed by a client. As each connection is formed ormodified, a portion of the total policy information potentiallyapplicable to that connection is identified and cached. In theembodiment of FIG. 3, upon establishment of a connection, QoS inspectionmodule 328 selects the policy information from QoS policy registry 324and client policy registry 326 that is potentially applicable to theconnection and caches it in a form that can be readily applied as eachdatagram is sent.

In this context, “connection” refers generally to predeterminedinformation about some or all of a communication path between a clientand another device, or to predetermined information about some or all ofa communication endpoint on a client. The format of a connection mayvary depending on the communication protocol used. For example, devicescommunicating using TCP protocol establish connections that aresometimes called sessions. A session involves communication from oneapplication component in a client computer to another applicationcomponent in a remote device. If the same application component in theclient wants to communicate with a different application in the remotedevice, a different session is established. For a TCP connection,establishing a connection may allow QoS inspection module 328 toidentify all aspects of a policy applicable to that connection.

On the other hand, devices communicating with a UDP protocol establishcommunication endpoints that describe only portions of the communicationpath from one application to another. When a datagram is sent using anendpoint, the datagram includes header information that identifies theapplication that originated the datagram and the application that is thedestination for that datagram. Full information about the path is notavailable until the datagram is generated, but the informationassociated with a UDP “connection” nonetheless may allow portions of thepolicy to be identified as irrelevant to the connection.

The amount of information about the transmission path specified when aconnection is created—or conversely the amount of information that mustbe specified about the transmission path when a datagram istransmitted—may dictate the amount of information about quality ofservice policies that needs to be stored in order to apply the policiesto datagrams as they are transmitted through the connection. For a TCPconnection, the full path is specified when the connection isestablished, which may allow all of the policy information to beevaluated to select transmission characteristics in accordance with thepolicy.

For a UDP connection, aspects of the policy that depend only on thesource application or user name for the datagram can be evaluated. But,any aspects of the policy information that depend on the specific sourceor destination device, or destination applications, can not be evaluateduntil the datagram is generated. Thus, the portion and format of thepolicy information that is cached for a connection may depend on theprotocol used for that connection.

In the embodiment pictured in FIG. 3, the quality of service policy isselectively applied such that transmission characteristics selected inaccordance with the policy are applied to datagrams when the client isconnected to a managed network. When the client is not connected to amanaged network, no quality of service information is applied todatagrams. Though not described in specific examples herein, a qualityof service policy may be selectively applied in other ways. For example,different quality of service policies may be applied based on whetherthe client is connected to a managed network.

To facilitate selective application of a quality of service policy,information about the type of network connection used for each ofnetwork interfaces 215A . . . 215C is stored in a fashion that it can bereadily accessed when a datagram is being processed for transmission. Inthe embodiment illustrated, NLA 221 calls into network stack 314 towrite information into each of the network interfaces 215A . . . 215Cindicating whether the network with which the network interfaceinterfaces is a managed network. Field 335 in network interface 215A isshown in FIG. 3 to hold information about the network type. In thisexample, a single bit is sufficient to identify whether a networkinterface interfaces to a managed network. In the examples shown, field335 contains a value of “1,” indicating that network interface 215Ainterfaces to a managed network.

As datagrams are generated for transmission through network interface215A, field 335 may be accessed to determine whether transmissioncharacteristics should be set in accordance with a quality of servicepolicy. Similar fields for other network interfaces may be accessed wheninformation is transmitted through those interfaces. The information infield 335 may be used in any suitable manner to control application ofthe quality of service policy. For example, network stack 314 mayexamine the value of field 335 and forgo a call to QoS policy component320 when the value in field 335 is 0. Alternatively, network stack 314may place a call to QoS policy component 320, which may in turn read thevalue in field 335. When the value in field 335 indicates that thedatagram for transmission will not be transmitted over a managednetwork, QoS policy component 320 may specify transmissioncharacteristics that do not limit transmission or processing of thedatagram.

FIGS. 4A-4C illustrates how policy information may be cached to reducethe computational burden when a datagram-by-datagram application of thepolicy information is performed. FIG. 4A illustrates a data structurecontained within QoS policy registry 324. In this example, QoS policyregistry contains all of the policy information applicable to a client.Where a separate client policy registry, such as client policy registry326, is used, the policy information in that registry may also be usedin determining a portion of the policy information applicable to aconnection.

In the embodiment illustrated, each policy is represented as a rule.Each rule is stored as a record in the data structure. Records 410A,410B . . . 410N are illustrated in FIG. 4A. Each of the records 410A,410B . . . 410N is shown to contain multiple fields. Taking record 410Aas illustrative, the record contains a condition field 412. Conditionfield 412 contains information defining the conditions under which therule applies. The specific conditions for each rule depend on thequality of service policy for the applicable network. However, theconditions may specify characteristics of a datagram, such as the sourcedevice, the destination device, the source application or thedestination device. In this example, any number of conditions orcombinations of conditions may be specified and condition field 412 maycontain any desired number of subfields to store the requiredinformation.

Each of the records also contains fields defining transmissioncharacteristics that are to be applied when the rule is applicable. Inthe example of FIG. 4A, two transmission characteristics are specified.Accordingly, each record contains two transmission characteristic fieldsdefining transmission characteristics to be used for datagramssatisfying the conditions specified in the condition field. Again takingrecord 410A as illustrative, a throttle field 414 and a DSCP field 416are shown to specify transmission characteristics. These fields store athrottle value that may be provided to control driver 216 when adatagram is transmitted and a DSCP code that may be inserted into aheader for a datagram.

The number of fields and type of data stored in each field is forillustration only. In clients equipped to control transmissioncharacteristics other than a throttle rate and a DSCP code, furtherfields may be included to specify transmission characteristics.Alternatively, fewer fields may be included for clients that have lessability to control transmission characteristics.

FIG. 4A shows QoS policy registry 324 also includes an field 430. Field430 stores a value indicative of the epoch or time at which QoS policyregistry 324 was last updated. As described above, information in QoSpolicy registry 324 is periodically retrieved by policy service 250. Aswill be described below, the time stored in field 430 is used to ensurethat current information available is used in setting transmissioncharacteristics for a datagram.

Regardless of the form in which policy information is stored, uponestablishment of a connection, a portion of the policy information iscached. FIG. 4B shows an exemplary data structure 440 containing a cacheof connection information. In this example, data structure 440represents data associated with UDP connections.

Data structure 440 contains a plurality of records, of which records442A, 442B and 442C are illustrated. Each of the records corresponds toa connection and contains fields providing data that allows a quality ofservice policy to be applied to each datagram transmitted through theconnection.

Taking record 442A as illustrative, the record contains a field 444identifying the connection. The data stored in field 444 may be in theformat used by applications sending messages to identify the connectionthrough which the message is to be transmitted. Storing data in thisform reduces the computation required to select an appropriate one ofthe records 442A, 442B and 442C to use when applying a quality ofservice policy to each datagram. However, any suitable format may beused for information stored in connection field 444.

Record 442A also includes a flag field 446. For a UDP connection, thepolicy information stored in QoS policy registry 324 may make any numberof rules applicable to a connection. In the illustrated embodiment, flag446 provides a convenient way to identify the number of rulespotentially applicable to the connection described by a record and maybe used by a component applying the record to a datagram. In theillustrated embodiment, flag field 446 contains one of three values toindicate whether the record contains multiple rules applicable to aconnection, a single rule applicable to a connection or no rulesapplicable to a connection.

Record 442A illustrates the structure of a record containing multiplerules. Record 442B illustrates the structure of a record containing norules. Record 442C illustrates the structure of a record containing asingle rule. Regardless of the number of rules, each rule may be storedin the same format.

For example, record 442A contains fields 448A . . . 448M, each storinginformation about one rule. Information about a rule could be stored inany convenient fashion. For example, fields such as 448A . . . 448Mcould contain pointers to a record in QoS policy registry 324. However,in the described embodiment, each rule is stored by copying the recordin QoS policy registry 324 corresponding to the rule.

FIG. 4B shows that data structure 440 includes an field 450. Field 450stores a value indicating the time at which data structure 440 wasupdated. In some embodiments, the value in field 450 is set by copyingthe value in field 430 when data structure 440 is created or updated.When data structure 440 is used to compute a transmission characteristicfor a connection, it is possible to quickly determine whether datastructure 440 was formed using the most up to date policy information bycomparing the value in field 450 to the value in field 430. If the valuein field 430 indicates a later time than the value in field 450, datastructure 440 is potentially out of date and may be recomputed for thepolicy information in QoS data structure 324.

FIG. 4C provides an example of a data structure 460 that may be used tostore a portion of the policy information associated with TCPconnections. As with data structure 440, each connection is representedby a record in the data structure, of which records 462A, 462B and 462Care shown. Taking record 462A as illustrative, each record contains afield 464A identifying the connection. In the present example, once aconnection is specified using the TCP protocol, all information neededto apply all the policy rules is available. Accordingly, storing aportion of the policy information involves storing only the transmissioncharacteristics dictated by the policy information. Accordingly, record462A contains a data field 464B storing the transmission characteristicsassociated with a connection. The transmission characteristics stored infield 464B may be stored in a suitable format. In this example, field464B may store data in the form stored in fields 414 and 416.

FIG. 4C shows that data structure 460 also includes an field 470 storinga time value. As with field 450, field 470 is used to identify when theinformation in data structure 460 is out of date.

Here, data structures 440 and 460 are shown as separate data structures.Any suitable partitioning of the data may be used, including storinginformation about multiple types of connections in a single datastructure. If information about multiple types of connections is storedin a single data structure, a field may be included for each record inthe data structure indicating the type of connection, which would thenindicate the number and types of fields contained in the record.Alternatively, identifying the connection may, in some instances,provide sufficient information to identify the type of connection.

Turning now to FIG. 5, a method of operating a client computer toimplement a quality of service policy is shown. In an enterprisenetwork, each client computer may operate according to a process asillustrated in FIG. 5.

The process of FIG. 5 may be performed by software running on a clientcomputer and may be performed by the operating system software of aclient computer having the architecture as illustrated in FIG. 3 andusing data structures as illustrated in FIGS. 4A . . . 4C. However, theprocess blocks shown in FIG. 5 represent functions that can be readilyimplemented in many ways by one of skill in the art and any suitableimplementation may be used.

The process of FIG. 5 includes two sub processes. Sub process 520 occurswhen a connection is established. Sub process 540 occurs when a datagramis transmitted. These processes are shown in FIG. 5 as sequentialbecause a connection is established before a datagram is transmittedthrough that connection. However, these sub processes could each beimplemented as separate processes of a multi-process device.

The overall process begins at block 510 where the software waits for aconnection. In a client, a connection is generally established by a callfrom an application program to components within the operating system.In some embodiments, the process of FIG. 5 is initiated by the operatingsystem component that is called to establish a connection.

When a connection is established, sub process 520 is performed to storea portion of the overall policy information that could be applicable tothe connection. As described above, policy information may be availableto a client from multiple sources. In some instances, a quality ofservice policy may be specified by thousands of rules. Processing atblock 522 selects a subset of these rules. The selected rules are theones that will always be applicable to a datagram transmitted throughthe connection or rules that may be applicable to such datagrams,depending on parameters associated with the datagram when it isgenerated.

Once the potentially applicable rules have been identified, processingcontinues to decision block 524 where the process flow splits based onwhether the connection being established is a TCP connection. In theembodiment described, policy rules are specified based on conditionsthat can be evaluated at the time a TCP connection is established.Accordingly, if a TCP connection is specified, the transmissioncharacteristics for that connection may be computed at block 526 byapplying the rules selected at block 522. The transmissioncharacteristics may then be stored for the connection. That informationmay, for example, be stored in a data structure such as data structure460 (FIG. 4C), including a value identifying when the rules used tocompute the cached information were last updated.

Alternatively, if the connection to be established is not a TCPconnection, processing proceeds for decision block 524 to block 530. Atblock 530, the potentially applicable rules selected at block 522 arecached at block 530. The rules may be cached in a data structure such asdata structure 440 (FIG. 4B), including a value identifying when therules used to compute the cached information were last updated.

The process then continues to block 532 until a datagram fortransmission is identified. When transmission of a datagram isinitiated, the sub process 540 is performed. In some embodiments, subprocess 540 may be initiated when stack 314 places a call to QoSinspection module, requesting transmission characteristics for adatagram.

As an initial step in sub process 540, the type of network through whichthe datagram will be transmitted is determined at step 541. In anembodiment with software architecture as pictured in FIG. 3, the type ofnetwork may be determined by reading a field, such as field 335, from anetwork interface through which the datagram will be transmitted.

The specific network interface through which the datagram is to betransmitted may be determined in any suitable way. For example,conventional network layer software may associate a local address witheach datagram identifying a connection through which the datagram willbe transmitted. The local address may identify a network interface to beused for transmitting the datagram. For TCP connections, each localaddress may be associated with a network interface at the time theconnection is established. For UDP communications protocol, each localaddress may not be associated with a network interface until thedatagram is generated. Regardless of the time at which an associationbetween a local address and a specific network interface is defined, bythe time processing reaches block 541 in the process illustrated in FIG.5, information associated with the datagram will be sufficient toidentify the specific network interface through which the datagram is tobe transmitted. Because each network interface contains data specifyingthe type of network over which it transmits, identifying a networkinterface for each datagram allows information on the network to beobtained on a datagram-by-datagram basis.

With the information on network type, processing proceeds to decisionblock 542. At decision block 542, the process branches based on whetherthe network over which the datagram will be transmitted is managed. Ifthe network is not managed, processing proceeds to block 543 where thedatagram is transmitted, without application of a quality of servicepolicy.

However, if the network is managed, processing proceeds to decisionblock 544. The process branches at decision block 544 based on the typeof connection through which a datagram will be transmitted. If theconnection is not a TCP connection, the process branches to block 548.At block 548, applicable transmission characteristics are computed usingthe rules cached at block 530. Alternatively, if the connection is a TCPconnection, processing proceeds to block 546 where the transmissioncharacteristics cached at block 528 for the connection are retrieved.

Regardless of how the transmission characteristics are determined,processing the proceeds to block 551 where the transmissioncharacteristics are applied to the datagram. When the process of FIG. 5is performed on a client computer having a software architecture aspictured in FIG. 3, transmission characteristics are applied byreturning to stack 314 values representative of the transmissioncharacteristics. Stack 314 then provides those values to driver 216 foruse in transmission of the datagram. However, any suitable method oftransmitting a message with the specified characteristics may be used.

Once the transmission characteristics are applied according to thequality of service policy, the process proceeds to step 553, where thedatagram is transmitted.

Such a process allows a client computer to operate with a quality ofservice policy when it is connected to a managed network, regardless ofwhether it is located within an office 101 or a remote site, such as auser's home 161. Alternatively, when the client computer is used toconnect to non-managed networks, transmission is not delayed by applyingthe quality of service policy. As described above, the client mayautomatically switch between modes in which the quality of servicepolicy is not applied. Moreover, the client may switch between modes ona datagram-by-datagram basis with very low overhead. This capabilityallows datagrams sent to a managed network to be interspersed withdatagrams sent to a non-managed network, with the application of thepolicy being driven by functions performed by the user of the client.

Having thus described several aspects of at least one embodiment of thisinvention, it is to be appreciated that various alterations,modifications, and improvements will readily occur to those skilled inthe art.

For example, the embodiment of FIG. 1 illustrates communication within anetwork, but application of the invention is not limited to any specificnetwork or network configuration. For example, though FIG. 1 showspolicy information stored in database 114 connected through a server 112to clients within enterprise network 100, no specific storagearchitecture for centralized policy information is required. Centralizedpolicy information may be provided from a router or other network deviceor may be provided from one client to another or may be individuallyloaded into each client computer. Policy information may alternativelybe provided from locations outside of network 100. Further, embodimentsof the inventions may be constructed without the use of centralizedpolicy information at all.

As another example, quality of service policies have been described thatspecify transmission characteristics to influence the latency ofdatagrams. The concepts described herein are applicable to policyinformation that influences any transmission characteristic ofdatagrams. Further, the concepts described herein are not limited tocontrolling datagram characteristics and may be applied to implement apolicy that influences user perception of network operation bycontrolling any other operational characteristic.

Also, FIGS. 4A . . . 4C illustrate data structures useful for TCP andUDP connections. Though TCP and UDP are the most common protocols inuse, a system may be constructed to work with other protocols. Similardata structures can be used in connection with other protocols.

Also, though not expressly shown in FIG. 5, subprocess 540 may includechecking whether updates to the qualify of service policy are available.If policy updates are available, the process may include updating thepolicy information and recomputing the cached policy information.

Such alterations, modifications, and improvements are intended to bepart of this disclosure, and are intended to be within the spirit andscope of the invention. Accordingly, the foregoing description anddrawings are by way of example only.

The above-described embodiments of the present invention can beimplemented in any of numerous ways. For example, the embodiments may beimplemented using hardware, software or a combination thereof. Whenimplemented in software, the software code can be executed on anysuitable processor or collection of processors, whether provided in asingle computer or distributed among multiple computers.

Also, the various methods or processes outlined herein may be coded assoftware that is executable on one or more processors that employ anyone of a variety of operating systems or platforms. Additionally, suchsoftware may be written using any of a number of suitable programminglanguages and/or conventional programming or scripting tools, and alsomay be compiled as executable machine language code or intermediate codethat is executed on a framework or virtual machine.

In this respect, the invention may be embodied as a computer readablemedium (or multiple computer readable media) (e.g., a computer memory,one or more floppy discs, compact discs, optical discs, magnetic tapes,etc.) encoded with one or more programs that, when executed on one ormore computers or other processors, perform methods that implement thevarious embodiments of the invention discussed above. The computerreadable medium or media can be transportable, such that the program orprograms stored thereon can be loaded onto one or more differentcomputers or other processors to implement various aspects of thepresent invention as discussed above.

The terms “program” or “software” are used herein in a generic sense torefer to any type of computer code or set of computer-executableinstructions that can be employed to program a computer or otherprocessor to implement various aspects of the present invention asdiscussed above. Additionally, it should be appreciated that accordingto one aspect of this embodiment, one or more computer programs thatwhen executed perform methods of the present invention need not resideon a single computer or processor, but may be distributed in a modularfashion amongst a number of different computers or processors toimplement various aspects of the present invention.

Computer-executable instructions may be in many forms, such as programmodules, executed by one or more computers or other devices. Generally,program modules include routines, programs, objects, components, datastructures, etc. that perform particular tasks or implement particularabstract data types. Typically the functionality of the program modulesmay be combined or distributed as desired in various embodiments.

Various aspects of the present invention may be used alone, incombination, or in a variety of arrangements not specifically discussedin the embodiments described in the foregoing and is therefore notlimited in its application to the details and arrangement of componentsset forth in the foregoing description or illustrated in the drawings.For example, aspects described in one embodiment may be combined in anymanner with aspects described in other embodiments.

Use of ordinal terms such as “first,” “second,” “third,” etc., in theclaims to modify a claim element does not by itself connote anypriority, precedence, or order of one claim element over another or thetemporal order in which acts of a method are performed, but are usedmerely as labels to distinguish one claim element having a certain namefrom another element having a same name (but for use of the ordinalterm) to distinguish the claim elements.

Also, the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having,” “containing,” “involving,” andvariations thereof herein, is meant to encompass the items listedthereafter and equivalents thereof as well as additional items.

1. A method of operating a computer system comprising a clientconnectable to a network, the method comprising: a) sensing a networkcharacteristic with the client; and b) transmitting a datagram with theclient using a quality of service policy selected in response to thesensed network characteristic.
 2. The method of claim 1, wherein sensinga network characteristic comprises determining whether the network is amanaged network.
 3. The method of claim 2, wherein determining whetherthe network is a managed network comprises identifying a domaincontroller in the network.
 4. The method of claim 1, wherein sensing anetwork characteristic comprises obtaining an IP address of a domaincontroller.
 5. The method of claim 4, wherein the domain controller isassociated with a domain and transmitting the datagram using the qualityof service quality comprises using a policy of service policy associatedwith the domain.
 6. The method of claim 2, wherein transmitting adatagram using a quality of service policy comprises inserting a qualityof service parameter in a header of the datagram.
 7. The method of claim2, wherein transmitting a datagram using a quality of service policycomprises modulating a transmission rate based on the quality of servicepolicy.
 8. The method of claim 1, further comprising: c) generating thedatagram with an application executing on the client, the applicationbeing unchanged to implement the quality of service policy.
 9. Acomputer-readable medium adapted for use on a client computer, thecomputer-readable medium having computer-executable componentscomprising: a) a network interface adapted to provide datagramsconfigured for transmission over a network, the network interface havingassociated therewith a data field adapted to store a valuerepresentative of a type of the network; and b) a first componentadapted to provide to the network interface information representingdatagrams for transmission over the network and to provide a quality ofservice parameter, the quality of service parameter being selectivelyprovided based on the value of the data field.
 10. The computer-readablemedium of claim 9, wherein the first component comprises: i) a qualityof service component adapted to provide a quality of service parameter;and i) a network stack component adapted to receive a message fortransmission over the network, the network stack component adapted to:A) receive a quality of service parameter from the quality of servicecomponent in response to receiving a message through the stackinterface; and B) provide a datagram to the network interface inconjunction with the quality of service parameter, the quality ofservice parameter being selectively provided based on the value of thedata field.
 11. The computer-readable medium of claim 9, furthercomprising: c) a second component, coupled to the network interface, thesecond component being adapted to determine the type of the network andprovide the value to the network interface.
 12. The computer-readablemedium of claim 9, further comprising: c) a second network interfaceadapted to provide datagrams configured for transmission over a secondnetwork, the second network interface having associated therewith asecond data field adapted to store a second value representative of atype of the second network.
 13. The computer-readable medium of claim12, wherein the second network adapter is a VPN adapter.
 14. Thecomputer-readable medium of claim 9, further comprising: c) a drivercomponent adapted to receive a datagram through the network interfacefor transmission over the network, the driver component being adapted tocontrol a characteristic of transmission of the datagram in response tothe quality of service parameter.
 15. A method of operating a computersystem having a client, the method comprising: a) while the client is ina first location: i) connecting the client to a first network; ii)transmitting a first datagram from the client using a quality of servicepolicy; b) while the client is in a second location: i) transmitting asecond datagram over the first network using the quality of servicepolicy; and ii) transmitting a third datagram over a second networkwithout using the quality of service policy.
 16. The method of claim 15,wherein the client is a portable computer, and the first location is anoffice and the second location is outside the office.
 17. The method ofclaim 15, further comprising, c) while the client is in the secondlocation, connecting the client to the first network using a VPNconnection.
 18. The method of claim 17, further comprising d)transmitting a plurality of first type datagrams using the VPNconnection, each of the first type datagrams being transmitted using thequality of service policy.
 19. The method of claim 18, wherein thesecond network comprises the Internet.
 20. The method of claim 19,further comprising e) transmitting a plurality of second type datagramsover the Internet, the plurality of second type datagrams beinginterspersed with the plurality of first type datagrams.